Process and furnace for making mineral wool



Oct. 13, 1936.

E. R. POWELL PROCESS AND FURNACE FOR MAKING MINERAL WOOL Original Filed July 27, 1928 INVENTOR fpW/mo 7?. POWELL.

as a charge-receiving intake.

Patented Oct. 13, 1936 PATENT OFFICE PROCESS AND FURNACE FOR MAKING MINERAL WOOL Edward R. Powell, Alexandria, Ind., assignor, by

mesne assignments, to Johns-Manville Corporation, New York, N. Y., a corporation of New York Application July 27, 1928, Serial No. 295,675

REISSUED Renewed January 31, 1935 7 Claims. (01. 49-775) This invention relates to a furnace for the economical production of mineral fibre, commonly called rock wool.

The chief object of this invention is to produce economically, with a minimum of waste and at a relatively rapid rate, a molten stream of mineral material suitable for blasting into mineral wool.

A feature of the invention consists in the utilization of relatively powdered fuel whereby an intensiflcation in action is obtained, and relatively fine raw material falls in counter-current relation to the flame so that the raw material is surrounded on all sides by the flame.

Another feature of the invention is to provide a large bath or pool of melted material so the various ingredients will have opportunity of mixing and reacting and from which two or more streams of nearly equal size may be drawn.

Another feature of the invention is that, by varying the different blast pressures and since there is a slight difference in viscosity between the several streams, the material or wool formed from each combination can be regulated to either produce a substantially uniform material or as preferably desired, a material having coarse as well as fine fiber, and the two types of material when intermingled produce final material of good mechanical strength as well as good insulating value and to a degree not obtainable with a single nozzle furnace.

The full nature of the invention will be understood from the accompanying drawing and the following description and claims:

In the drawing Fig. 1 is a vertical section of one embodiment of a furnace including the invention. Fig. 2 is an end view of the spout or discharge end of the furnace.

In the drawing, it indicates a combustion chamber of refractory material such as carborundum or chromite block encased as at H forming an air passage l2 therebetween into which extends veins I3 of the refractory wall for furnace cooling. The combustion chamber includes a discharge outlet for the gases which also serves The combustion chamber has one or more spouts or tap holes l5 from which discharge the molten streams l6 which are blasted by air or steam supplied as at ii to form the mineral fiber or wool.

The means for combustion are supplied through with some air. Air is supplied through pipe 20,

AUG 1 6 1938 is carried to the blower 2| through the pipe 22 connected at 23 to the chamber l2, which cham- I ber has an open face at its opposite end so that air will be drawn through the chamber taking heat from the refractory wall. The air passed through the blower to the discharge assists in the discharge of the powdered fuel, such as coal. The hot air and the fuel burn completely and the flames and the gases pass forward through the combustion chamber and upwardly through the stack 25 suitably insulated as at 26, and pass from said stack to the smoke pipe 21 and thence to the chimney. To assist in the production of the steam employed in the blast H, a water jacket 28 is included in the stack construction.

Positioned at the top of the stack is a hopper 30 having a control discharge in the form of a measuring device such as a measuring screw 3| at the outlet 32 therefrom. The material in the hopper 30 consists of the mineral or rock to be melted, and, preferably, such mineral or rock is in the form of pieces of relatively small size, that is, it is crushed to about one-half inch or smaller. The crushed mineral is introduced into the combustion chamber by a gas and material flow arrangement, such that it enters the combustion chamber at substantially the melting point and in a melting condition.

Means for securing this operation consists in alternate baflies 33 arranged to cause the departing gases to take a sinuous path and the entering material to take a similar coincidental but re-' verse path. The cold material is intimately contacted by the colder portion of the gases, and, as the crushed mineral approaches the combustion chamber, its temperature rises as also does the temperature of the stack, by reason of the increase in temperature of the gases as the combustion chamber is approached. The material is in such condition both as to size and to temperature so that when the same leaves the last baille 33, it is almost ready to discharge into the combustion chamber, and at a melting temperature or has just started to melt.

The stack-discharged, melting, crushed material passes through the flames or is heated thereby and is completely melted and collects at the bottom in the stream bed 35. In all probability there is also formed in said stream bed a cone 36 of unmelted. rock. The molten bath at the stream bed is drawn oil through the tap holes l5.

The present invention permits the utilization of small pieces of mineral and thus the employment of a conveyor system from the mine to the furnace, if the. distance between the two be not excessive. But. more important than this is the change from coke to a powdered fuel, such as coal. This reduces the fuel cost approximately or more. The use of relatively fine or crushed mineral does not require a long temperature contact period to melt the smaller particles. Also, the small size of the mineral particles permits each particle to be intimately contacted by the hot gases passing from the combustion chamber so that the raw material is preheated substantially to the melting point before it discharges into the combustion chamber and, by reason of the small size of the said material, contact with the flames in the combustion chamber immediately melts the mineral and the liquid is ready for discharge through the tap holes. Thus, a very high temperature is obtained at the melting point of the material thereby providing a better physical condition of the molten mineral which in turn permits the production of better fibre or a greater proportion of a commercially acceptable fibre.

Another economy in operation consists in utilizing the heat radiating from the combustion chamber for pre-heating the air supplied to the fuel. This, while apparently insignificant, is of considerable importance, since the temperature of the air does not have to be raised to the heat of the furnace at the melting point from that of the atmosphere. The temperature of the furnace in the interior at the contact point of the flame and the mineral material is between 3000 and 3500 degrees Fahrenheit or thereabout. The introduction of air under ordinary temperatures to the interior of a furnace with the before-mentioned temperature therein would involve an un necessary fuel loss and cooling of the furnace.

the ascending gases of combustion and herein the condition of this character is illustrated by the cold air discharge pipe I00 connected to a header I 0| in turn connected by line I22 to a fioor I20 controlled by a valve I20. This arrangement insures positive cooling to the adjusted degree. If desired, the blower may be omitted and the header intake or intakes suitably controlled so that the draft in the stack will serve to direct into the stack a suitably adjusted amount of cool air. The result is that pro-melting of the material, while passing through the stack, is prevented and clogging of the melted material in said stack is thus prevented.

As shown clearly in Fig. 2, the present type of furnace readily lends itself to multiple spout discharge. In this way a plurality of spouts I! can discharge into a single blow chamber and the capacity of the unit be doubled by the addition of one or more additional spouts without requiring any appreciable additional equipment, thus materially reducing plant operation but securing increased production without any material. injuries in attendance or maintaining charges or capital investment. The rate of flow of the material through the stack can be regulated to take care of the desired number of outlets or spouts.

As shown in Fig. 1 each of the blasts l'I may be controlled by a valve Ill so that the pressure may be regulated. Since the sheets l6 discharge from different parts of the furnace, and since the temperature may vary slightly, said streams discharging are for slightly different viscoslties.

The several streams having a slightly different viscosity and the several blasts or nozzles I! having different pressures can produce any final type of material and such a material will include a mixture of materials made under different conditions, that is, one nozzle may blow a coarse strong fiber and another nozzle may blow nothing but fuzz. These two extreme types of materials when intermingled in the'blow chamber H0 having the opening H0 produce a material of good mechanical strength as well as good insulating value and to a degree not'obtainable with a single nozzle.

The invention claimed is:

1. The method of manufacturing molten material for rock and mineral wools which come prises maintaining a blast flame of pulverized fuel, maintaining a supply of raw material, withdrawing a continuous relatively thin stream of material from said supply, preheating said stream of raw material by passing it in countercurrent relationship to the products of combustion from said flame, controlling said preheating operation whereby said raw material, at the end thereof, is substantially atits melting temperature, projecting said preheated material directly across said flame, whereby it is melted, collecting said melted material in a pool, and withdrawing said melted material from said pool at points of different temperature in a plurality of streams in the presence of a plurality of jets, whereby said molten material is formed into wool.

2. The method of manufacturing mineral wool which comprises maintaining a pool of the molten rock, supplying sufficient heat to said pool to maintain its fluidity and withdrawing said material in a plurality of streams from different points of temperature of said pool and contacting a jet with each of said streams whereby said molten material is formed into wool.

shredding the material in the several streams into mineral wool, and intermingling the wool produced from the several streams.

5. The method of manufacturing mineral'wool insulating material comprising the steps of reducing a mineral material to form a plurality of molten streams, shredding the streams by blasts to produce different types of textured fibre, and intermingling the types of fibres.

6. The method of manufacturing mineral wool insulating material comprising the steps of reducing a mineral material to form a plurality of molten streams, shredding the streams by independently controlled blasts to produce different types of textured fibre, and intermingling the types of fibres.

7. The method of producing mineral wool which comprises, placing rock into a furnace, melting the rock to form a pool, discharging said molten rock directly from said pool in a plu-v rality of discrete streams, and discharging a gaseous medium under pressure against said streams at such velocity as to disintegrate said streams to form rock wool fibres.

EDWARD R. POWELL. 

